This invention relates to a data interface for transferring information relating to the performance of an inductive loop detector of the kind used for detecting the passage or presence of vehicles. The information which is transferred relates to the operation, and to the fault diagnosis, of the detector which consists of an inductive loop and a detector unit to which the loop is connected.
It is known to provide a vehicle detector of the kind described with a visual output indicator and to pulse or flash the indicator slowly to transmit information on the status of the inductive loop detector, thereby to transfer such information to an operator. The pulse rate is sufficiently low to ensure that a human operator may observe and count or evaluate the pulses. The transmission of information in this way may be initiated by the operator and, after the transmission is completed, the inductive loop detector resumes normal operation.
It is known to extract information from an inductive loop vehicle detector by means of a physical electrical connection made directly thereto. The information is normally, but is not limited to, data gathered by the detector relating to the passage or presence or vehicles, for example vehicle counts.
The first mentioned technique is of necessity slow and laborious and is subject to human failing. On the other hand the second technique, although it does not unduly interfere with the normal operation of the detector, is inappropriate for reasons of complexity, inconvenience and cost.